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Thread: A Method for Assembling Flex Shafts using Loctite

  1. #1

    Default A Method for Assembling Flex Shafts using Loctite

    I was putting together some flexshafts this past week and thought maybe someone here could benefit from some explanation and pics.

    I'm using Loctite 638 this time around. I normally use the thinner 603, but Steven recommended I try this. It's definitely thicker and seems to flow well enough to get down into the cable winds.

    I also use the Loctite 7471 Primer, but I know of others who just use Acetone. I'm using both, in this case.

    20160107_192807.jpg

    First, you'll want to cut your cables to the appropriate length. I simply cut mine about 1/4" longer than I want the completed length with a set of heavy duty wire side cutters, then I sand the ends of the cable down on a sanding disc to get it as square as possible:

    20160107_193150.jpg

    20160107_193203.jpg

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  2. #2

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    You also want to be sure the clean out your stub-shafts. The process of drilling out the cable end leaves residue and cutting fluids. I use a Q-Tip soaked with Acetone and clean them out well, until the Q-Tip comes out clean and dry. As you can see from the picture, I chuck the Q-Tip up in a cordless drill and use that to assist the process.

    20160107_193708.jpg

    Clearly a lot of residue left behind! Clean this all out.

    20160107_193726.jpg

    Finally, I use some wed-dry 220-grit to clean up the end of the cable. I chuck the cable up in my drill, then rotate it and sand the end until the gold/bronze is gone and the end of the cable is cleaned up.

    20160107_193338.jpg

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    Clean up the end using some Acetone to remove any residue and dry it well. You can even use a little bit of heat from a heat gun or ??? to make sure you completely dry out the windings of the cable. When it's all cleaned up, it'll look something like this:

    20160107_193530.jpg

  3. #3

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    With all the parts cleaned up, you can now start assembling.

    One topic that came up recently was how to keep everything lined up while the Loctite is setting. The way I do it for a .150" cable and a .130" flex, is to use a piece of 7/32" and a piece of 3/16" tubing, one to hold the stub, the other to hold the cable. They two pieces of tubing slide into each other and will hold them VERY closely inline.

    20160107_192227.jpg

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    Put a controlled amount of Loctite onto the last 1/2" or so of the flex, all the way around. Also, put a drop or so into the stub-shaft.

    20160107_193948.jpg


    When you push the cable into the stub, it may "hydraulic" a bit. Make sure you rotate the flex and push in until it's fully seated. Do this slowly so you don't force all the Loctite out, but rather into the cable windings.

    You WILL get a little bit of squeeze-out. Gently wipe this off, trying to leave a little right at the top of the stub. It will soak in as the Loctite sets. Just make sure you get it off the sides of the stub-shaft.

    20160107_194055.jpg

  4. #4

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    Finally, making sure that there isn't any overflow of Loctite on the sides of the stub or the cable, slide the stub into the larger piece of tubing and support it vertically using a shop clamp or ???

    20160107_191647.jpg

    20160107_194140.jpg

    Slide the smaller piece of tubing over the flex and partially into the larger piece of tubing to support and center the flex. DO NOT push the flex-shaft support tuning all the way to the top of the stub. Leave it up 1" or so, just to keep it from possibly getting bonded to the assembly.

    Set aside and let it setup. I let mine sit at room temperature for a 24-hour period, just to make sure the Loctite if fully cured.

    20160107_192327.jpg


    If all goes correctly, you'll be able to just slide the brass/aluminum tubing off, run some Scotchbrite over the stub and cable, and you'll have a completed Flexshaft, ready to install.

    Hope this helps.

  5. Default

    Nice tutorial especially for those of us who are visual learners.
    "Our society strives to avoid any possibility of offending anyone – except God.”
    Billy Graham

  6. #6

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    Someone should put a sticky on this one

    Very well done Darin.

    Larry
    Past NAMBA- P Mono -1 Mile Race Record holder
    Past NAMBA- P Sport -1 Mile Race Record holder
    Bump & Grind Racing Props -We Like Em Smooth & Wet

  7. Default

    Stuck it is

    Quote Originally Posted by TRUCKPULL View Post
    Someone should put a sticky on this one

    Very well done Darin.

    Larry
    "Our society strives to avoid any possibility of offending anyone – except God.”
    Billy Graham

  8. #8
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    Darin acetone will indeed clean grease or oil out but I prefer stuff that is made for that job, Loctite 7061 superclean or 7063 superclean.

  9. #9

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    Quote Originally Posted by martin View Post
    Darin acetone will indeed clean grease or oil out but I prefer stuff that is made for that job, Loctite 7061 superclean or 7063 superclean.
    That's fine. Probably just a version of Brake Parts Cleaner or ??... The idea is simply to degrease and dry the area and leave no residue.

  10. #10

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    Nice job Darin very easy directions to follow.

  11. #11

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    I was curious, I purchased a .187 flex cable with 3/16 propshaft from OSE. I ended up cutting a little more than half of the cable off, I am wondering if I can make a backup cable if I purchase another 3/16 propshaft? I only see 3/16" propshaft for a .150" cable.
    NEVER SATISFIED RACING
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  12. #12
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    You use the 3/16" propshaft with the .150" hole, you have to remove the outer winding on the 3/16" flex. The outer winding is removed the depth of the hole, the flex & propshaft is then brazed together. When you remove the outer winding of the flex it leaves the flex at .150" that goes into the hole.

  13. #13

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    The benefit of 603 is that its oil tolerant. Meaning that if there is any residual oil left behind in the cable it won't screw u the whole assembly.

    Darin, you should maybe do a 3/16 cable with a 3/16 stub. Kind of a PIA.
    glue sniffer

  14. #14

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    Ah, never mind. Martin is on it.
    glue sniffer

  15. #15

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    Quote Originally Posted by martin View Post
    You use the 3/16" propshaft with the .150" hole, you have to remove the outer winding on the 3/16" flex. The outer winding is removed the depth of the hole, the flex & propshaft is then brazed together. When you remove the outer winding of the flex it leaves the flex at .150" that goes into the hole.
    If you do this, is there any benefit to using 3/16" cable when it terminates with .150" anyway??
    Club Galvatron

  16. #16

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    Quote Originally Posted by ray schrauwen View Post
    If you do this, is there any benefit to using 3/16" cable when it terminates with .150" anyway??
    Yes because if you notice all the 3/16 assemblies the flex cable is hard soldered the last 1/4 to 1/2" to the prop shaft.
    Steven Vaccaro

    Where Racing on a Budget is a Reality!

  17. #17

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    I'm sorry. I was under the impression that someone was trying to use Loctite for this.
    Club Galvatron

  18. #18

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    I agree, as far as I know loctite can't be used with those.

  19. #19
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    Quote Originally Posted by ray schrauwen View Post
    If you do this, is there any benefit to using 3/16" cable when it terminates with .150" anyway??
    Of course there is if you braze the two pieces and re-join the outside braids with molten material. It is then centerless precision ground back to 3/16”. I wouldn’t trust a glued assembly in this application. Many do it, but I put my faith in metal!

  20. #20
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    When you braze a 3/16" flex in the method I outlined above both the 150 part of the flex is brazed into the stub hole & the butted part of the 3/16 joint is brazed as well. You simply cant use Loctite on this type of joint where it is 3/16" flex going onto a 3/16" stub. Chopped up pieces of brazing rod along with flux is put down into the bored hole in the stub before inserting the flex prior to heating the assembly, further rod is added at the butted joint to complete the brazing job.

  21. #21
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    The chopped pieces is interesting... I use the hole as a molten metal pot, then bring the flex in from the top, slowly heating it as I insert into the hole. There is extra in there that will flow out around the sides, and some of that is what attaches to the outer cut strands. The procedures sound pretty close to me...

  22. #22
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    Yep same sort of idea, you must also keep the torch flame towards the stub & let the heat travel to the flex otherwise you risk getting the flex to hot if you put to much flame directly on the flex for to long & annealing the flex.

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